Mostly Harmless
by dnachemlia
Summary: Peace. Quiet. Safety. Those are the things he had hoped to have when he made this world his home. It was the perfect existence, until the conflict he escaped years ago raised its ugly head again. Written for the NFA What Planet Are You From? Challenge.
1. Prologue

Mostly Harmless

Written for the _What Planet Are You From?_ Challenge

Genre: Sci-Fi/Suspense/AU (well, as far as we know ;) )

Rating: FR 15/T

Characters: Tim, Jimmy, and the rest of the MCRT

Summary: Peace. Quiet. Safety. Those are the things he had hoped to have when he made this world his home. It was the perfect existence, until the conflict he escaped years ago raised its ugly head again.

Disclaimer: don't own, at all, ever. *sigh*

* * *

_**Prologue**_

Tim McGee guided his vehicle along the rough dirt road towards his destination, a scenic overlook about a mile off Skyline Drive, far away from the noise and light pollution of the city. Soon he reached the end of the road and pulled off onto a flat area before putting his car in park and turning off the engine. There were no other cars present and Tim smiled. He would be able to enjoy the night sky in peace.

He climbed out of his car and grabbed a blanket from the trunk before he carefully made his way to a large, flat-topped boulder. He spread the thick coverlet over the rock and climbed up on top where he lay down on his back, gazing at the vastness above him. The night was clear and surprisingly cool for late summer, providing much needed relief from the heat and humidity he had experienced earlier that day.

Tim started to relax as his eyes became adjusted to the darkness and he let out a soft sigh of pleasure. Quiet moments like these were rare indeed. Normally he would still be at work, delving into an array of computer-based searches and ignoring the prattle of his teammates, but tonight luck had been with him: the case that had occupied them for the past two weeks had finally been closed and Gibbs had sent them all home at a reasonable hour. Tony and Ziva had asked him to join them for drinks but he had declined. He had really needed to get away, to decompress after a tough case, and he had simply told them he was going home to sleep. Tony made a few comments about his need to get out more, and Ziva had gently urged him to try and have some fun with them, but he had begged off and managed to leave without further questions. He expected some teasing in the morning but he didn't mind. It was worth it for a few hours of solitude and his _real_ favorite activity – stargazing. He chuckled softly to himself as he imagined what his teammate's reaction would be to the truth.

As he became accustomed to the lack of artificial light, Tim scanned the sky for a particular arrangement of stars and soon found the familiar grouping known as the Summer Triangle. In the city, if he had been able to see the stars at all, he would have only been able to discern the three brightest: Deneb, Vega, and Altair, which formed the three points of the Triangle. Out here, however, he could see the other constellations from which the brightest stars in each formed the simpler shape: Cygnus the Swan, Lyra the Lyre, and the formation that always drew his interest, Aquila the Eagle.

It was not the particular shape, nor the symbol behind the constellation itself that captured Tim's interest, but the section of the sky in which it was found. While most would have focused on the closest and brightest in the group, Tim looked beyond to an almost invisible star, much further away. It was a object of which most astronomers were unaware, and hadn't even given a proper name. Tim knew of it, and also knew of the small planet which circled that star.

A place he had once called home.

It had been nearly twenty years since he had been forced to flee his birthplace, to escape through a portal which brought him to this planet, so similar to his home world and yet so different. Despite the fact that he had made a new home here, a _good _home, and a good life in place that offered what he and his family had been seeking, he still felt the occasional tug of homesickness. His grandmother told him it was whimsy, that he was attached to the good memories and conveniently forgot the horror he had left behind, but still Tim clung to those memories as a remind of who…of _what_ he was.

His family had blended in here well. No one suspected that the green-eyed, lanky youth, his young curly-haired sister, and their rather eccentric grandmother were not of this world. He had done enough background research to know what would have happened if they had not been able to blend in, part of the reason he often kept people at arm's length. Finally, after several years of being with a team that practically lived in each other's pockets, he had started to relax a little. He could keep up the illusion of relatively normalcy almost effortlessly. The worries that had colored his early years had faded, and now, for the most part, he would be comfortable in admitting that he felt safe and content.

If only he could be certain that contentment would last…

XXX

Seventy-five miles away, in a rather non-descript section of the nation's capital, Marine Sergeant Aloysius "Al" Gannon stumbled along the broken sidewalk towards the spot where he had parked his car. He had spent the evening out drinking with two of his buddies, and after pouring them both into a cab and paying the cabbie to take them back to their respective apartments, he had decided to sleep off some of his own indulgence before driving home himself.

He reached the vehicle and fumbled with his keys for a moment before they slipped from his fingers and hit the pavement. Muttering a few colorful phrases he had learned from his first drill sergeant, he bent down to retrieve them. As he did so, he noticed a strange glow reflected in the side of his car and turned to find its source. An eerie blue-white light emanated from the alley in front of him and he blinked, wondering if he'd had more to drink than he remembered.

As he cautiously approached the alley he thought he heard someone speaking, but the words were unlike any language he had heard before. He paused and listened, noting that the voice sounded almost mechanical, similar to what had heard over coms while in the field during his most recent tour in Afghanistan. Wondering if this was some strange alcohol-induced dream, he moved closer to the alley and finally caught sight of the speaker. He had just enough time to let out a cry of surprise before a searing pain burned through his chest and the world around him vanished in a flash of brilliant white light.

TBC…


	2. Chapter 1

**Mostly Harmless**

Chapter 1

Tim made it to his desk with barely a minute to spare and let out a small sigh of relief. He had fallen asleep out in the park and awoke as the night sky had begun to lighten to grey, slightly stiff and sore from his less-than-comfortable sleeping place and cold and damp from the early morning dew that had settled over him. A quick glance at his watch had told him he didn't have time to go home, so he had taken advantage of the gym showers once he reached NCIS, glad that he had remembered to re-stock his "go bag" recently. After hastening through his usual morning routine—minus his morning coffee—he rushed upstairs ready to start the day, albeit a bit rumpled.

Tony, not one to miss an opportunity to comment when something was amiss, turned toward Tim with an almost predatory gleam in his eye as the younger man dropped into his chair.

"Rough night, McGee?"

Tim took a steadying breath and plastered on a calm yet disinterested expression.

"No, it was fine. Slept surprisingly well."

"And where was that, McGee? Not at your apartment—we stopped by to check on you."

Tim groaned inwardly, annoyed at their terrible timing. "Just because I didn't answer the door—"

"Your car was not there, either," Ziva added, showing concern rather than the amusement her partner displayed. "Did something happen to it?"

"No, nothing happened." Tim glanced up at his teammates and decided that this time an edited version of the truth would probably give him the least amount of trouble. "I decided to go for a drive, and since it was such a clear night last night I decided to do a little star-gazing. I fell asleep out in the park. End of story." Tim saw a flash of confusion in Tony's eyes before the other man grinned.

"Only you, McGee." He returned to his desk and started to work on his computer, and soon Ziva did the same. The group was quite for a few moments before Tony broke the relative silence.

"See anything interesting while you were out there?"

"Just the stars, Tony. They're interesting enough." An inexplicable twinge of homesickness hit him and Tony immediately noticed the slight pause.

"You're hiding something, Probie. Does that mean you _did_ see something? A UFO, maybe? Oh, I know!" Tony's grin grew wider. "You were abducted by aliens, but they brought you back 'cause they feared the wrath of Gibbs."

"They're not the ones who should," growled the lead agent as he strode into the bullpen and Tony ducked instinctively, eliciting a smirk from Ziva. "Grab your gear. Dead Marine in Capitol Heights." The team scrambled to follow Gibbs to the elevator and Tim let out a soft sigh of relief. Hopefully the case would be enough of distraction to steer Tony away from his personal life once again.

XXX

Metro was on the scene when they arrived and the team followed Gibbs as he went to confront the detective in charge.

"What do we got, Sportelli?"

"Glad this is one of yours instead, Gibbs. You people seem to attract the weird ones." Gibbs sent the man one of his patented glares and Sportelli chuckled. "Patrol officers found the body early this morning in that alley back there. Our techs ran his prints: Marine Sergeant Aloysius Gannon. His vehicle is still parked next to the alley," he added as he pointed to a black PT Cruiser with a Virginia license plate. "He's stationed at Quantico."

"So what's 'weird' about this one?" asked Gibbs.

"Wait until you see the body. At any rate, it's all yours." Sportelli nodded to his officers and they moved aside to allow Gibbs' team entrance to the alley, surprisingly clear of trash and other debris. The body was lying on its back just a few feet from the entrance and Ducky immediately knelt down next to the prone form. He let out a small gasp of surprise when he bent to examine the wound, and the rest of the team drew closer.

"What is it, Duck?"

Ducky continued to examine the area around the wound and carefully touched the edge with one gloved hand before he turned to Gibbs. "I must admit, Jethro, I've never seen anything quite like this." Gibbs leaned over Ducky's shoulder and took a closer look at the surprisingly bloodless damage.

"Does that-?"

Ducky carefully rolled the body on its side to examine the back. "It goes all the way through, and the edges appear to have been instantly cauterized."

"No blood at all," muttered Palmer. "That's…"

"Freaky," finished Tony. "Maybe it was your aliens, McGee." He turned to the junior agent and was surprised by the look on the younger man's face. "What's wrong?"

Tim jumped slightly and shook his head. "Sorry, I… That's definitely weird. The lack of blood, I mean. Do you think this was a dumpsite? He was killed somewhere else and that's why there's no blood?"

"Weren't you listening? The guy didn't bleed at all. _That's_ the weird part. I'm with Ducky. I've never seen anything like this, either. What do you think, Boss?"

"I think we need to process the scene. McGee, shoot and sketch. Ziva, bag and tag. DiNozzo, start tracking down Gannon's platoon, find out who saw him last."

"On it, Boss."

Tim moved away from the body, thankful for the excuse to do so. He had managed to cover his shock fairly well, but he suspected Gibbs' hadn't been fooled, but at least he had time to come up with a better story. That was not, however, his biggest concern. Ducky may not have seen a wound like that before, but _he_ had, and the significance of its presence had sent a cold stab of dread into his heart.

Something was out there looking for him. Why now, and why here, he wasn't completely sure, but one thing was certain. He had to find it, and fast, before it found him.

XXX

The rest of the morning was spent searching the scene and doing the neighborhood canvas. A bartender from the bar down the street from where Gannon was found said that he had seen the Marine leave the bar with his two buddies after last call, and had called a cab before the trio had left. A search of local cab companies revealed that Gannon's companions had been picked up and returned to their respective residences, and the driver declared that they'd barely been capable of walking when they were dropped off. The bartender also told the team that he had seen Gannon's car still parked where it had been found when he was closing up, and had believed that Gannon was sleeping off a night of drinking when the bartender left the area. There were no other witnesses to the events that had taken place in the wee hours of the morning and no working security cameras that covered the area, much to the chagrin of the team.

The scene search revealed very little evidence, and no trace of Gannon's attacker. Abby voiced her frustration to Tim but he was secretly relieved. It made his job easier, since he wouldn't have to dodge awkward questions that would most certainly have arisen if what had killed Gannon _had_ left any evidence of its presence.

On the way back to NCIS, Tim sent a quick text message to Penny, using a code they had established many years ago, which he knew she would understand: get Sarah and get out of the area as soon as possible. He was grateful that this was one thing she would argue with him over, and could only hope that Sarah would cooperate. He didn't want to have to worry about his family while he was hunting the unwelcome visitor.

Tim went through the motions of investigating, doing background searches on Gannon himself, as well as helping Abby search for an implement that could have caused the damage to the Marine. After a more thorough examination, Ducky had admitted that the weapon _could_ have been a sharp metal object that had been heated enough to create the effect, although he had found no traces of metal in the wound itself. Unfortunately that further complicated the question of how Gannon had wound up in the alley in the first place. They started treating it as secondary crime scene, but there were still no indications of where Gannon could have been taken prior to being dumped in the alley, or how he had been removed from the scene and returned.

Tim tried to make himself as unobtrusive as possible as he followed Gibbs' barked orders and watched the tension levels climb when each new search or file accesses ultimately led to a dead end. Finally, when it became apparent that there was nothing else they could do that night, Gibbs sent them all home with the order to be back in the office by 0600. When he was certain the others had gone, Tim made his way down to autopsy to get a better look at the damage done to Gannon.

The cold room was silent, and Tim carefully opened the drawer enough to see the wound in the man's chest. He held his hand over it, measuring the diameter of the hole, as that bit of information would tell him something about who, or _what_, had wielded the weapon.

"What are you doing?"

Tim looked up and saw Palmer standing in the doorway. The agent bit back a curse and quickly withdrew his hand.

"Nothing, Palmer. I just came down for another look. We're still trying to figure out what caused this and I thought I might get a few more ideas for a search."

"Tony thinks it was a ray gun or something," Palmer said with thinly disguised enthusiasm. "Maybe a new secret weapon…or aliens."

"Tony watches too many movies," Tim muttered.

"True," Palmer replied with a grin. "Besides, why would aliens just kill a single Marine? You'd think they'd go for a bigger target."

_Unless they were only after a __**specific**__ target_. "I really have no idea. What are you still doing here, anyway?" Tim asked, trying to get the younger man off on another tangent.

"Oh, I was studying. It's pretty quiet here. Makes it easier to concentrate. What are you doing here? I though Agent Gibbs sent everyone home?"

"He did. I was on my way out and decided to take a detour. You know, get an idea where to start tomorrow."

"Makes sense. I was just getting ready to head out myself. Come on, I'll walk out with you."

Tim really didn't want to waste any more time before starting his search, but it didn't look like he had much choice in order to avoid suspicion.

"All right, let's go."

Both men walked out to the parking lot and headed for their respective cars. Tim was almost to his vehicle when he heard a startled exclamation from Palmer.

"_McGee, look out!"_

Tim spun and instinctively ducked as a beam of energy shot towards him. He rolled and swept one leg out at the dark shape approaching, knocking it to the ground before it could fire again. A bolt of pain shot through his leg as it connected with the attacker but he clenched his teeth and threw himself on top of it, pinning it momentarily before it started to buck wildly. His hands scrambled across its surface as he searched for its weak spot. Finally, just as he feared it would gain the upper hand again, he found the spot he was seeking, grabbed the small ring of metal as hard as he could and yanked. He felt his attacker grow still beneath him and breathed a sigh of relief.

"_What in the hell?"_

Tim looked up to see Palmer standing a few yards away, looking more freaked than Tim had ever seen him. _Great…_

"What…what _is_ that?"

Tim rolled off the attacker and got to his feet as he stared down at the thing sent to destroy him. It looked human on the outside, but the mass of wires the Tim had pulled free destroyed that illusion. "I really don't think you want to know."

Palmer looked up at Tim, then back down at Tim's attacker, repeating the movement twice before a stubborn expression appeared on his face. "Yeah, I think I do. What is that thing? Why did it go after you, and…how did you know how to stop…it." Tim saw realization dawn on Palmer's face as the younger man's eyes widened. "Did that…was that what killed…?"

"Sergeant Gannon? Probably, but I have no idea why. It shouldn't have fired at anything other than its target."

"You?" Tim nodded. "But why?"

"That's a long story," Tim muttered and was surprised to hear a nearly hysterical laugh.

"I think I'm used to those by now."

"Yeah, good point." Tim glanced around, surprised that no one had come to see what the commotion was about, and noticed the lights on the security cameras were out. _That would explain it._ He wasn't ready to explain his secret to anyone, let alone the Autopsy Gremlin, but the current situation had limited his options.

"Listen, Jimmy, I'll tell you what I can, but first," he pointed to the thing at his feet. "I have to get this out of here. I don't have much time." Much to Tim's surprise, Palmer merely nodded and bent down to lift the feet of the attacker. Tim recovered quickly and grabbed the arms as the two of them dragged it over to his Porsche. He popped the trunk and they managed to get it inside and shut the lid.

"Now what?" Jimmy asked, looking for all the world like he was having the time of his life.

"I need to take it back to the alley. I'm pretty sure that's where it came through."

"Came through from where?" Jimmy's eyebrows shot up. "Wait, did this come from the future? Like _Terminator_?"

Tim groaned. "No. Look, I'll explain later, but—"

"Got it. Well, what are we waiting for?" Jimmy hurried to the passenger side and climbed in. Tim paused for a moment, not sure what he was getting himself into. Finally he climbed in the driver's seat and carefully drove out of the Yard. As he made his way back to the alley, he decided that things could be worse. At least Palmer wouldn't make _too_ many movie references along the way.

He hoped.

TBC…

One more chapter to go.


End file.
